Process for coagulating polymer lattices prepared in a true aqueous emulsion



March 23, 1954 E, G H KQLVQQRT 2,673,193

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O IOZO SOAOSOGOTO 8090\00 METHYL E HYL COMP COAGULANT, VOL. /o \SOAMVLALCOHOL -KETONE \nygrflofi Egbe r lis Hendrik Kolvoorf Attorney PatentedMar. 23, 1954 PROCESS FOR COAGULATING POLYMER LATTICES PREPARED IN ATRUE AQUEOUS EMULSION Egbert Cornelis Hendrik Kolvoort, Amsterdam,Netherlands, assignor to Shell Development Company, Emeryville, Calif.,a corporation of Delaware Application August 13, 1951, Serial No.241,566 In the Netherlands December 13, 1946 Section 1, Public Law 690,August 8, 1946 Patent expires December 13, 1966 Claims. 1

This invention relates to a process for coagulating polymer dispersions.More particularly, the invention relates to a process for coagulatingpolymer lattices prepared in a true aqueous emulsion.

Specifically, the invention provides an eflicient and highly economicalprocess for coagulating stable dispersions of polymers of unsaturatedorganic compounds prepared in a true aqueous emulsion which comprisesadding to the said 26, 1947, now abandoned.

Aqueous method.

bination with the electrolyte.

of electrical appliances, etc.

polymer dispersions.

2 yields polymers having improved physical properties. It is a furtherobject to provide a method for coagulating polymer lattices that may beaccomplished with relatively small quantities of coagulating agents andin a short period of time. It is a further object to provide a methodfor coagulating polymer lattices in true aqueous emulsions that gives asubstantially complete coagulation. It is a further object to provide amethod for incorporating a plasticizer with the polymer This novel Inad- 10 aqueous emulsion certain organic substances deduring thecoagulation. Other objects and adscribed hereinafter in an amount whichis suffivantages of the invention will be apparent from cient to f a p rani phase n h the following detailed description thereof. ins h r ultinmixt p r b y at h boil- It has now been discovered that these and ingtemperature of the said mixture. other objects may be readilyaccomplished by the This application is a continuation-impart of novelprocess of the invention which comprises y pp t on S No. L fi cembadding to the aqueous emulsions containing the dispersed polymer anorganic material which is emulsion polymerization p t a liquid under thecoagulating conditions, is misv al a es Ov t known polymerizacible withwater in limited proportions only and tiOn methods, Such s u and pensionpolydissolves very little if any of the polymeric mamelization, and theCommon monomers such as terial and is selected from the group compris-Vinyl Chloride, are gehsl'ally polymeriZed y this 'ing alcohols,ketones, acetals, carboxylic acids,

The p v is not entirely others, halogenated hydrocarbons, phenol, mix-Sa a tory, p arly because of the difficultures thereof, or mixtures ofthe foregoing comties encountered in finding a suitable method forpounds d th organic substances indicated coagulating the p y p o sformed in hereinafter, in an amount which is suflicient to the emulsion.The methods suggested heretofore form a separate organic phase and thenheating for the coagulation of the dispersions include th resultingmixture, preferably at the boiling subjecting the emulsion to freezingtemperatures, 90 temperature of th aid mixture. adding an E oly such assodium chloride, process has been found to bring about a substanadding asolvent which is entirely miscible with tially complete coagulation ofthe dispersed polyllhe aqueous phase, such s ethyl alcohol mers and theresulting polymer particles have acetone, an adding t s b solvent ingreatly improved physical properties, particularly The first 13W) as tomechanical stability and hardness. methods are generally undesirablebecause of the dition, t resulting polymer particles have a high costsinvolved in their operation and because very 1 ash cgntent d they arideally suited 0f the 0W Qua y Of the resulting polymers for use as anelectrical grade polymer. Afurther Polymers coagulated with electrolytesgenerally advantage of the process li i the f ct that the have high ashcontents and are unsuited for 40 Coagulation may be accompnshed by theaddia y app such as in the manufacture tion of only relatively smallquantities of the co- The Coagulation of agulating agent and thecoagulant that is added the dispsrsiOhs by the addition of the Water canbe recovered at the end of the process by discible solvents has thedisadvantage of requiring tm t th t having any erious efieet on thelarge amounts of the solvent to accomplish the color and mechanics]properties f the polymer. desired degree of coagulation, and in additionre- The polymer dispersions t b coagulated by q Considerable time andequipment for the process of the invention are those obtained bycovering the large quantities of solvent employed. homopolymerizmg orcopolymerizing ethylen- It therefore, an Object of the invention toically unsaturated organic compounds in a true provide an improvedmethod for coagulating aqueous emulsion. Examples of such dispersions Itis a further Object to are those prepared by polymerizing in an aqueousprovide E efficient a highly economical emulsion monomers, such as theunsaturated method for coa u p y lattices p p esters of the saturatedmonocarboxylic acids, as i a u aqueous ul It s a urther object allylacetate, vinyl valerate, methallyl caprylate', and ethallyl formats; theunsaturated esters of to provide a method for coagulating polymerlattices prepared in true aqueous emulsion that the unsaturatedmonocarboxylic acids, such as allyl acrylate, vinyl methacrylate,butenyl crotonate, 4-heptenyl 3-butenoate, and 3-pentenyl sorbate; theunsaturated aliphatic poly-esters of saturated polybasic acids, such asdiallyl malonate, allyl ethyl tartar-ate, and the like; the unsaturatedaliphatic polyethers of saturated polyhydric alcohols, such as diallyland dimethallyl ethers of glycol, diethylene glycol, trimethyleneglycerol, and similar derivatives of diglycerol, manitol, sorbitol, andthe like; the unsaturated aliphatic organic acid poly-esters of thepolyhydric alcohols, such as acrylic and methacrylic poly-esters ofglycol; the unsaturated polyesters of dibasic aromatic acids, such asdiallyl phthalate, dimethallyl phthalate; the sulfolanyl carbamate, suchas methyl 3-sulfolanyl carbamates, and ethyl 3-sulfolanyl (N-methyl)thiocarbamate.

A preferred group of monomers to be polymerized in the aqueous emulsionare those containing a CH2=C= in their molecule, such as the butadienes,piperylene, isoprene, chloroprene, the aromatic vinyl compounds, such asstyrene, alpha-methyl styrene, the nitriles and esters of the acrylicand alpha-substituted acrylic acids, such as methyl methacrylate,acrylonitrile, as well as the vinyl and allyl derivatives of the variousacids, ethers, ketones, etc.

Particularly preferred monomers to be polymerized in the emulsion arethose possessing a single CH2=C= group and having a molecular weight ofnot more than 225, such as vinyl chloride, allyl acetate, vinylidenechloride, methyl methacrylate, styrene, methylstyrene, allyl valerate,vinyl valerate, and the like. An especially preferred group of monomersto be polymerized are the monomers of the group consisting of vinylchloride, vinylidene chloride, methyl methacrylate and isobutene.

The importance of the invention is particularly in evidence, however,when applied to the coagulation of the homopolymers and copolyrners ofthe vinyl halides, such as vinyl chloride and vinyl bromide;

Any of the emulsifying agents customarily employed in emulsionpolymerization of such polymerizable unsaturated organic compounds maybe employed. These include particularly the ionic surface active agents,especially those having a polar structure including a hydrophilic(predominantly hydrocarbon) residue and a charged (ionic) radicalthereon, such as anionic surfaceactive compounds including alkali metaland nitrogen-base soaps of higher fatty acids, such as potassium and/ orsodium myristate, laurate, palmitate, oleate, stearate, ammoniumstearate, etc., as well as the surface-active compounds of thecation-active variety, such as salts of long-chain aliphatic amines andquaternary ammonium bases, such as lauryl amine hydrochloride, ste-'aryl amine, hydrochloride, and palmityl amine hydrobromide. Additionalexamples of suitable ionic surface-active emulsifying agents include thealkali metal or ammonium alkyl or alkylene sulfates or sulfonates, suchas sodium and/or potassium lauryl sulfate, alkyl, aryl and alkylatedaryl sulfonates, cetyl sulfonate, oleyl sulfonate, stearyl sulfonate,sulfonated Turkey red oil, sulfonated mineral oils, sodium, potassiumand ammonium iscpropyl naphthalene sulfonate, amine soaps, such astriethanolamine stearate, aminosubstituted alcohols, sulfonated fattyesters and amides, the hydrochloride of diethyl aminoethyloleylamide,trimethylcetyl ammonium methyl sulfate, alkanesulfonic acids, alkalimetal and ammonium salts of sulphonated long-chain hydrocarbons, orsulphonated long-chain fatty acids, such as sulphonated oleic acid andthe sodium, potassium and ammonium salts of sulphated cetyl alcohol.Starch, gum-arabic, the polyoxyalkylene oxide condensates of hexitananhydrides, carboxymethylcellulose, etc. may also be used. Theseemulsifying agents are organic-solvent stable and as a whole alkalistable; that is unlike, for example, proteins, they are not chemicallyaltered upon solution or dispersion in organic solvents and aregenerally stable in the presence of alkali, such as aqueous solutions ofcaustic alkali. Proteins as a group are not organic-solvent stable oralkali-stable.

The amount of the emulsifying agent employed in the preparation of thestable emulsions will vary over a considerable range depending upon theparticular unsaturated organic compound to be polymerized, the type ofemulsifying agent, the amount of water, and the kind and amount of otheringredients added thereto. In general the amount will vary from about.1% to about 10 76 by weight of the water present in the reactionmedium. The preferred amount of the emulsitying agent to be employedwill vary between about .5% and about 5% by weight of the water presentin the reaction medium.

The aqueous emulsion in which the polymer dispersion is prepared may beacid, alkaline or neutral. As the subsequent coagulation process ispreferably accomplished in an alkaline medium, it is generally preferredto conduct the polymerization in an alkaline emulsion, i. e. an emulsionthat has a pH of at least '7, so that there will be no need tosubsequently adjust the pH of the solution for the coagulation. The pHof the original emulsion may be brought to the desired level by theaddition of any suitable agent, such as NaOH, and the like.

The polymerization may be effected in the aqueous emulsion by theapplication of heat, light and polymerization catalysts, or any desiredcombination thereof. Any of the known polymerization catalysts, such asthe per-acids, such as persulfuric acid, peracetic acid, and perphthalicacid, the per-salts, such as potassium persulfate, the peroxidecatalysts, such as hydrogen peroxide, benzoyl peroxide, succinylperoxide, lauryl peroxide, dibutryl peroxide, sodium peroxide, tertalkylhydroperoxides, such as tert-butyl hydroperoxide, and the like, may beused with success in the polymerization. If desired, mixtures of thecatalysts may be employed. The amount of the catalyst employed may varyover a considerable range depending upon the various conditions ofreaction. In most cases, the amount of catalyst will vary between about.01% to about 5% by weight of the material to be polymerized. Apreferred amount of catalyst will vary between 191% to 2% by weight.

The total amount of the polymerizable material to be added to theaqueous emulsion may vary over a considerable range depending upon thenature of the various ingredients and the amount of water present in theemulsion. In most cases it is preferred to maintain the ratio ofpolymerizable material to water smaller than 1 to 2. When the ratio islarger than 1 to 2 the emulsion, in some cases, becomes too thick to behandled efliciently and the results are not as satisfactory as desired.The preferred ratio of the p'olymerizable material to the water in theemulsion mixture varies between about 1 to 3 and 1 to 5.

Temperatures employed during the aqueous emulsion polymerization will,in most cases, vary between about C. to about 60 C. with a pre ferredrange being between about C. to about C. Atmospheric pressure is usuallythe preferred pressure to be employed.

The polymer dispersions prepared in the true aqueous emulsions arecoagulated according to the process of the invention by the addition ofan organic substance as described above in sulficient quantity to form aseparate organic phase and then heating the resulting mixture,preferably at the boiling temperature of the said mixture. The materialsused as coagulating agents are those organic substances that are liquidunder the coagulating conditions, are miscible with water in limitedproportions only and dissolve very little if any of the polymericmaterial and are selected from the group comprising alcohols, ketones,acetals, carboxylic acids, ethers, halogenated hydrocarbons, phenol,mixtures thereof, or mixtures of the foregoing compounds and otherorganic substances described hereinafter.

The organic substances used as the coagulating agents should have atleast some solubility in Water but the solubility should be limited. Thesolubility of the material may vary, for example, from .01 to 18 partsper 100 parts of water at the coagulating temperature or from 0.1 to 10parts per 100 parts of water at the coagulating temperature. Preferably,the solubility of the coagulating agent varies from the solubility ofdiamyl ether in water at the coagulating temperature to the solubilityof methyl ethyl ketone in water at the coagulating temperature.

The organic substances used as the coagulating agents should alsodissolve very little if any of the polymer to be coagulated. Thesolubility of polymer in the coagulating agent may vary, for

example, from no solubility to from 5 or 10 parts Examples of suchcompounds are butyl alcohol,

the amyl alcohols, particularly isoamyl alcohol, the hexyl alcohol,particularly sec-hexyl alcohol, methyl isobutyl carbinol, benzylalcohol, methyl ethyl ketone, isobutyl ketone, mesityl oxide, diet wleceta-l. isobutyric acid and Valerie acid. diethyl ether, diisopropylether and diamyl ether, trichloroethane and allyl chloride, and phenol,and mixtures thereof.

A preferred group of coagulants are the alcohols, ketones, ethers andacids containing from 3 to 12 carbon atoms and preferably from 5 to 9carbon atoms, such as amyl alcohol, isoamyl alcohol, hexyl alcohol,sec-hexyl alcohol, methyl isobutyl carbinol, octyl alcohol, valericacid, enanthic acid, methyl butyl ketone, diamyl ether, and the like.

Particularly preferred coagulating agents are the alcohols and acids,and particularly the aliphatic alcohols and acids, containing from 4 to6, and more preferably from 5 to 6 carbon atoms, such as amyl alcohol,isoamyl alcohol, sec-amyl alcohol, methyl isobutyl carbinol, hexylalcohol, isohexyl alcohol, 'val'eric acid, and the like.

It has'also been unexpectedly found that other substances that bythemselves do not give the desired coagulating action can be mixedwiththe aforedescribed agents to produce compositions having excellentcoagulating power. ,The resulting mixture of course should possess theabovedescribed properties of being miscible with water to a limitedextent only, of being a liquid under the coagulating conditions, and ofdissolving very little if any of the polymeric material. Hydrocarbonsare particularly important additives to be mixed with theabove-described substances. Examples of such hydrocarbons are gasoline,hexane, isooctane, cyclohexane, methylcyclohexane, toluene, benzene, andthe like.

Another important group of organic substances that do not by themselvesgive the desired coagulation but can be added to the above-describedagents to produce mixtures having excellent coagulating power are thoseorganic compounds which will have a plasticizing effect on the resultantpolymeric material. Examples of such plasticizers which may be admixedwith the coagulants are butyl acetate, dibenzyl phthalate, dioctylphthalate, dibenzyl succinate, cyclohexyl acetate, butoxyethyltetrahydrofuroate, sulfonamides, diethylene glycol dibutyrate,ethoxyethyl sebacate, triacetin, triamyl phosphate, tricresyl phosphate,dibutyl phthalate, triphenylphosphate, and the like. Preferredplasticizers to be used are those possessing at least one ester group intheir molecule. When these and other plasticizers are utilized in thecoagulant there appears to be a very uniform distribution of the saidplasticizer throughout the polymeric parti cles that are formed and theyin turn are very easily worked up per se or with other plasticizers toform the desired articles.

The amount of the above-described materials that may be added with thespecial coagulating agents and still obtain the desired coagulation willvary with the individual components and can easily be determined byconducting a few routine determinations.

Exceptionally fine results are obtained in the process of the inventionwhen the coagulant used is an alcohol, and preferably one of thepreferred alcohols containing from 5 to 9 carbon. atoms, and at leastone other organic substance, such as the liquid hydrocarbons andplasticizers described above. Examples of such coagulants which may beused to produce the exceptionally fine results are mixtures of isoamylalcohol and n-butyl acetate, isoamyl alcohol and gasoline, isoamylalcohol and methyl ethyl ketone, hexyl alcohol and methyl 'ethyl ketone,isoamyl alcohol and mesityl oxide, isoamyl alcohol and isobutyl ketoneisoamyl. alcohol and dichloro-ethane, octyl alcohol and isobutyl ketone,isoamyl alcohol and cyclohexane, isoamyl alcohol and trichloroethene,decyl alcohol and dichloroethane, and the like. Examples of mixtureshaving three or more components include mixtures of isoamyl alcoholbutylacetate-dichloroethane, isobutyl alcoholisoamyl alcohol-dichloroethane,and isobutyl alcohol-isoamyl alcohol-butyl acetate. When the threecomponent mixtures are employed, they generally produce coagulates thatare much coarser than those obtained with the binary mixtures.

The amount of the coagulating agent employed in the process should besufiicient to form an essential separate organic phase in the resultingmixture and preferably not substantially in excess ofthatamount. Theamount of the coagul'ant required for the formation of'this layer willvary with each particular case depending upon the solubility of thecoagulants in the aqueous medium, the temperature of reaction, etc. andmay best be determined for each individual situation.

It has been found to be of advantage to conduct the coagulation so thatthere will always be a clear aqueous phase left behind. When thisoccurs, the coagulation is obtained to a much higher degree, theproducts are more easily filtered, and the coagulate possesses improvedmechanical properties. The clear aqueous phase can be obtained bykeeping the quantity of the coagulating agent at the end of thecoagulation within certain predetermined narrow limits in proportion tothe quantity of the dispersion. This may be accomplished by' adding thedesired amount of coagulating agent at the beginning of the process, oralternatively, by adding at the beginning a greater quantity of agentthan is desirable or essential to obtain the desired effeet and thenafter the coagulation removing part of the agent, particularly bydistilling the reaction mixture. When in distilling the mixture thepoint is reached that the aqueous phase, after the settling, would beclear or practically clear, the distillation may be continued withoutdetriment to the effect already attained. A clear aqueous layer, forexample, is obtained when coagulating poly (vinyl chloride) by theaddition of 6 vol. per cent of isoamyl alcohol, or alternatively, byadding much larger quantities, e. g. 10 vol. per cent and then after thecoagulation removing the isoamyl alcohol by distillation until theminimum value has been reached or surpassed.

In case the coagulant utilized in the process of the invention iscomposed of a mixture of organic substances, e. g. the above-describedpreferred mixture of an alcohol and at least one other organicsubstance, the desired clear aqueous phase is obtained by maintainingthe ratio of the components in the mixture within certain limits and bykeeping the ratio of the amount of the separate phase formed by thecoagulant and the amount of the dispersion above a certain minimum valueand also preferably less than a certain maximum value.

The limits of the ratios referred to above are dependent on variousfactors. Moreover the limits of each of the ratios mentioned aredependent on the value of the other ratio. For each separate case thesuitable values can be determined experimentally. The relation betweenthe ratios can best be illustrated by the use of graphs such as thosedescribed in the examples at the end of the specification wherein theratios of the components in the coagulant are plotted against the amountof the coagulant in the suspension.

When using mixtures of components as the coagulating agent, it is alsopossible to obtain the clear water phase by first adding a greaterquantity of the mixture than is desirable or essential for obtaining thedesired favorable effect and then after the coagulation, removing thecoagulating agent until it reaches the minimum value. In this case also,the lower value may be exceeded in the removal Without the water phasebecoming turbid.

The amount of polymer dispersed in the aqueous emulsion may vary over awide range. -The preferred solutions to. be employed are those havingfrom to 33% by weight and .more

8. preferably from 15% to 30% by weight of the polymer dispersedtherein. More concentrated dispersions are preferably diluted with waterbefore being treated. Greater concentrations or smaller concentrationsthan the above may of course be treated if desired or necessary.

The aqueous emulsion to be used in the coagulation process may be acid,neutral or alkaline. The coagulation is preferably carried out in amedium that is neutral or alkaline, i. e. a solution having a pH of atleast 7. A neutral to weakly alkaline emulsion is particularlypreferred.

The mixture comprising the polymer dispersion and the coagulating agentis heated in order to bring about the desired coagulation (see Example11)). Th aqueous dispersion may be heated before addition of thecoagulating agent or the agent may be added to the dispersion and thecombined mixture then brought to the desired temperature. The mixture ispreferably heated above at least 50 C., and still more preferably at 100C. or the boiling temperature of the said mixture. An especiallypreferred range varies from C. to C. The length of the heating periodwill vary with the temperature employed and the particular polymer to be00- agulated but in most cases should not be more than 40 to 50 minutes,and preferably from 5 to 10 minutes.

It is generally desirable to accomplish the coagulation in as short aperiod as possible after the addition of the agent so as to prevent anysubstantial adsorption of the coagulating agent on the polymer particlethat may possibly occur in a few instances.

The dispersed polymer will begin to coagulate during the heating periodand at the conclusion thereof will settle to the bottom as more or lessround, hard and readily filterable particles of about equal size. Thecoagulate may be removed from the reaction medium by any suitablemethod, such as filtration and the like.

Volatile coagulating agents may readily be recovered by distillation atthe end of the process. They may be recovered from the total mixturebefore the coagulate has been separated or they may be recovered fromthe mixture after the coagulate has been removed. It is desirable inmost cases to remove the coagulating agent during the Washing of thepolymer pulp as it is more readily separated at that time from thecoagulate. As indicated a valuable advantage of the process of theinvention is the fact that the mixture containing the coagulating agentand the coagulate may be subjected to distillation without danger ofcausing any discoloration of the polymer particles.

The process of the invention may be conducted under atmospheric,subatmospheric or superat mospheric pressure. Atmospheric pressure ispreferred. The proce s may also be conducted in a batch-Wise,semi-continuous or continuous manner.

The coagulated particles obtained by the process of the invention willhave exceptionally fine mechanical stability as shown by theirresistance to rapid stirring, and in addition, have a very low ashcontent, i. e. a low amount of ashforming constituents, such asemulsifier, catalyst residue and inorganic salts. The coagulates mayreadily be worked up ina very smooth manner with any of the knownplasticizing agentsat room temperatures or higher temperatures. This 9characteristic is of particular importance as the smooth combination ofthe polymeric particles with the plasticizers at the higher temperaturesenables one to mill the components together without having any seriousaction on the color or mechanical properties of the final product.

The coagulates may readily be molded, cast into sheets, rods, tubes, andthe like of any desired shape or size. They may also be subjected toextrusion and to injection and compression molding in the presence orabsence of added diluents. They may also be utilized in solvent solutionin the production of surface coatings, impregnating agents, laminatinssolutions, and the like. The coagulates are of particular importance,due to their exceptionally fine electrical properties, in themanufacture of electrical equipment, insulations and the like.

To illustrate the manner in which the invention may be carried out thefollowing examples are given. It is to be understood, however, that theexamples are for the purpose of illustration only and they are not to beregarded as limiting the invention in any way.

Example I (a) An aqueous suspension of polyvinyl chloride was. preparedby polymerizing monomeric vinyl chloride in an aqueous emulsion of pH8-9,

2 parts of sodium cetyl sulfate as emulsifying agent, and 1 part ofpotassium persulfate as the catalyst. About 200 parts of this suspensionwhich contained about 33% by weight of polyvinyl chloride was dilutedwith 75 parts of water and mixed with about 27.5 parts of technicalisoamyl alcohol (boiling point 126-131" C.). The mixture was boiled for5 minutes under a reflux condenser and subsequently filtered through aBuchner funnel with filtering paper. The filter cake was washed fourtimes with water at about 50 C. and dried in vacuo at about 50 C. Ananalysis of the cake showed an ash content of between 0.1 to 0.2%. Thecolor of the product was very light.

(1)) Another suspension was prepared by polymerizing vinyl chloride inan aqueous emulsion of pH 8-10 with sodium lauryl sulfate as theemulsifying agent. About 200 parts of this suspension was diluted withwater as in (a) and then about 27 parts of technical.isoamyl alcoholadded and the mixture allowed to stand without any heat being applied.There was no noticeable coagulation of the polymer dispersion and it wasnecessary to heat the resulting mixture, particularly to at least about50 C. before the desired coagulation was obtained.

Example II About 50 parts of the aqueous emulsion described in Example Iwas diluted with about 25 parts of water after which about 40 parts ofdiethyl acetal was added. The mixture was heated up to boiling for 5minutes and was then easily filtered. After, several washings the cakewas dried at 50 C. The powder was then mixedwith tricresyl phosphate andturned into films,- some of which are pressedtogether, the temperaturebeing raised to 160 C. in 3 minutes and maintained at that level underconstant pressure for another three minutes. The resulting product is aclear, colorless, flexible compressed sheet possessing excellentelectrical properties.

Example About 350 parts of the emulsion described in 10 Example I wasdiluted with 175 parts of water and then heated up to boiling. Then 55parts of secondary hexyl alcohol was added. After a few minutes boilingthe mixture was cooled to about 80 C. and filtered. Further treatment asin Example I yielded a colorless product with an ash content to 0.27%.

Example IV The following table shows the results obtained when samplesof 33% polyvinyl chloride suspensions as prepared in Example I weretreated with the coagulants as indicated:

Water Coagulant Coagulant (1111.) (type) (quantity) Coagulatmntrichloroethane 6 Complete methyl ethyl ketone. 7. 5 Do. mesityl oxide25 Do. oleic acid 25 D0. diamyl cther 5 Do. sec-heptyl alcohol. 15Substantially complete. sec-cetyl alcohol. 20 Do. sec-nonyl alcohol.. 7.5 Complete. sec-hexyl alcoholl5 Do.

The coagulates in each case were readily filtered and dried to cakeshaving very low ash content.

Ezcample V About 200 parts of the suspension prepared according toExample I was neutralized with HCl to a pH of 7. Then 8 parts of isoamylalcohol and 12 parts of gasoline (boiling point 100 C. to 120 C.) wereadded. The mixture was heated to boiling for 5minutes and then filtered.Further treatment as outlined in Example I gave a colorless producthaving an ash content of 0.25%.

Example VI About 200 parts of a suspension of 30% by weight of polyvinylchloride prepared at a pH of 2.5 in the aqueous phase with about 2 partsof sodium cetyl sulfate as emulsifying agent and .4 part of hydrogenperoxide as catalyst was neutralized by the addition of NaOI-I. About 8parts of isoamyl alcohol and 12 parts of gasoline (boiling point to C.)were then added and the mixture was kept at 50 C. for 1 hour. Furthertreatment asdescribed in the preceding examples yielded a product withash content of 0.3%. The dried powder is combined with tricresylphosphate and cured at about C. for a short period of time. Theresulting product was a hard, flexible sheet, having excellentelectrical properties.

Example VII About 50 parts of the suspension prepared as in thepreceding example was neutralized and 5 parts of isoamyl alcohol added.After heating up to boiling for a few minutes the coagulation productwas readily filtered. Further treatment as mentioned in Example I,yielded an almost colorless product with a very low ash content.

Results comparable with those obtained in the above examples wereproduced with dispersions of polymers of vinlyidene chloride, methylmethacrylata and isobutene, and copolymers of vinylchloride withvinylidene chloride and copolymers ofvinylidene chloride and isobutene.

Example VIII Example IX About 300 parts of the suspension prepared as inthe preceding example was combined with 30 parts of methyl isobutylcarbinol and 10 parts of dichloroethane. The resulting mixture was thenboiled for 20 minutes. An azeotropic mixture of methyl isobutylcarbinol, dichloroethane and water was then distilled off (94-95" C.)The remaining mixture was filtered. The filtrate obtained was clear.After washing and drying, the resulting product had an ash content of0.2%.

Example X A 20% suspension of polyvinyl chloride was prepared bypolymerizing the monomeric vinyl chloride in an aqueous emulsion withsodium cetyl sulfonate as the emulsifier, potassium persulfate as acatalyst, and a pH of '8 to 9 at a temperature of about'35. C. Thesuspension was diluted with half its volume of water and about 3 partsof sodium bicarbonate per 1000 parts of the total mixture was added inorder to keep the pH at a suflicient level.

Approximately 6 vol. percent of isoamyl alcohol (calculated on the totalvolume of the suspension before the addition of the alcohol), was addedto the suspension mixture. The mixture was then kept at boilingtemperature for minutes.

After settling of the coagulate a clear top aqueous phase was obtained.Upon addition of larger as well as smaller quantities of the isoamylalcohol and aqueous phase remained turbid. The coagulate was very easilyfiltered to give a cake made up of particles of uniform size.

Example XI A suspension of polyvinyl chloride was prepared as in thepreceding example. vol. percent of isoamyl alcohol was added and themixture treated as above. When the mixture was centrifuged the topaqueous layer remained turbid.

Diiferent results were obtained, however, if after coagulation 7.5 vol.percent of the isoamyl alcohol was distilled off. In this case, aftercentrifugation the aqueous phase was perfectly clear.

Example XII A suspension of 20% polyvinyl chloride was prepared bypolymerizing monomeric vinyl chloride in an aqueous emulsion with sodiumcetyl sulfonate as the emulsifier, potassium persulfate as the catalyst,and a pH of about 8 to 9 and a temperature of 35 C. The suspension wasdiluted with half its volume of water, 3 parts of sodium bicarbonate per1000 parts of mixture was added in order to maintain the pH at thedesired value.

Mixtures of isoamyl alcohol and n-butyl acetate in varying ratioswerethen added to ind proportions.

12 vidual suspensions as prepared above in varying The resultingmixtures were then heated at boiling for about 5 minutes.

The results are shown in Figure I. In the graph, the composition of thecoagulant is plotted against the vol. percent of the coagulantcalculated on the volume of the water-diluted suspension. Each of thepoints in the hatched area correspond with the ratios which bring abouta clear upper layer after the coagulate has settled. Points lyingoutside the area relate to less favorable coagulation circumstanceswherein the water phase is turbid after the settlement of the coagulate.

Example XIII A series of experiments were conducted as in the precedingexample with the exception that the coagulant consisted of mixtures ofisoamyl alcohol and methyl ethyl ketone. The results of theseexperiments are shown in Figure II. Each of the points in the hatchedarea indicate the ratios which being about a clear upper layer after thecoagulate has settled and the points outside indicate the ratios thatwill give a turbid upper layer.

Similar diagrams occur when replacing isoamyl alcohol with otheralcohols and by replacing the n-butyl acetate or methyl ethyl ketonewith the following components; tricresyl phosphate, dibutyl phthalate,dioctyl phthalate, isobutyl ketone, mesityl oxide, dichloroethane,trichloroethane and chlorinated diphenyl, ethers, acetals and otherorganic substances. In a great number of cases the area favorable to theintended effect has a shape corresponding to some extent with thehatched areas in the accompanying graphs. Generally, the suitable areais bounded by two curves intersecting the axis of ordinates at a fairlyclose distance from each other. The lower limit mostly shows a minimumvalue. In some cases the rising branches of the two curves tend to runalmost parallel to the axis of the ordinates as in Figure I. In manyother cases, the rising branches of the curves are divergent as inFigure II.

In the following table, the approximate coordinates are listed ofvarious minima found in the coagulation of the above-describedsuspension.

The coagulates obtained in the above-described experiments werecharacterized by their excellent mechanical stability. The mechanicalstability was judged by their resistance to stirring, the criterionbeing the clearness of the top layer of the vigorously stirred andsubsequently centrifuged coagulated suspension. Stirring was effectedwith an L-shaped stirrer at approximately 1000 revolutions per minute.After the mixture was centrifuged, the clearness of the top was examinedafter 1, 3 and five minutes of stirring. In various cases, the top layerwas still entirely clear after being subjected to 5 minutesintensestirring and centrifugation.

while the microscopic picture of the coagulate had remained practicallyunchanged so that no diminution of the particle size could be observed.

The resistance to stirring is found to be dependent on the nature of theorganic substance added with the alcohol, on the ratio of thesecomponents in the coagulant and the volumetric ratio of coagulant todispersion. It was found, for example, that in the above series ofexperiments wherein the coagulant was a mixture of isoamyl alcohol andmethyl ethyl ketone, those mixtures having the alcohol and ketone inratio varying between 90:10 and 35:65 and the amount of coagulantremained at 10%, were able to produce coagulates having a resistance tothe 3 minute stirring.

Example XIV The suspension of poly(vinyl chloride) produced in Example Xwas coagulated by the addition of a mixture of 10% by volume of isoamylalcohol and 5.8% by volume of tricresyl phosphate and heating themixture to boiling for 5 minutes. After evaporation of the isoamylalcohol, filtration and washing, the poly(vinyl chloride) was obtainedas a fine powder. The powder was then rolled for 3 minutes at 155 C. andmolded at 160 C. for 3 minutes. The resulting, product was a clear,colorless, flexible sheet which was still found to contain the entirequantity of the tricresyl phosphate applied.

Example XV Different aqueous suspensions were prepared and treated withisoamyl alcohol as the coagulant and the resulting mixture heated toboiling. The results are indicated in the table below:

Percent Percent Percent 00am Monomers Emul- Catapl-I P Monomers Sifierlyst latlon 4O butadiene 25 10 .SPS 8 good. copolymer of vinyl l5 and10. 10 .45PS 8 Do.

chloride and vinylidene chloride. methyl methacrylate 25 1O .5PS 8 Do.

P-Potassium pcrsulphate. SSodium sulplilte.

Example XVI A suspension of a copolymer of vinyl chloride 0 andvinylidene chloride is treated with a series of coagulants as indicatedbelow and then heated to boiling. The results are indicated below:

I claim as my invention:

1. A process for coagulating a stable latex of a vinyl chloride polymerwhich latex has a pH of at least '7 and has been prepared bypolymerizing the said vinyl chloride in a true aqueous emulsioncontaining water, the vinyl chloride and, as the sole emulsifying agent,from 0.5% to 5% by weight based on the Water of an ionic surface activeagent which is organic solvent stable and alkali stable, which comprisesadding to the said latex a coagulating agent of the group consisting ofalcohols containing from 3 to 12 carbon atoms, mixtures of the saidalcohols with ketones containing from 3 to 12 carbon atoms, and mixturesof the said alcohols with liquid 76 hydrocarbons wherein the saidcoagulating agent is a liquid at the coagulating temperature and has asolubility in water at the coagulating temperature varying from thesolubility of di-- amyl ether to the solubility of methyl ethyl ketoneat the coagulating temperature and the solubility of the polymer in thesaid coagulating agent at the coagulating temperature does not exceedthat of the solubility of the polymer in methyl ethyl ketone at thecoagulating temperature, in an amount which is sufficient to form aseparate organic phase and heating the mixture of aqueous dispersion andadded coagulating agent at a temperature at least about C. to bringabout the coagulation of the dispersed polymer.

2. A process for coagulating a stable neutral to alkaline latex of avinyl chloride polymer which latex has been prepared by polymerizing thesaid vinyl chloride in a true aqueous emulsion containing water, thevinyl chloride and, as the sole emulsifying agent, from 0.5% to 5% byweight based on the water of an ionic surface active agent which isorganic solvent stable and alkali stable, which comprises adding to thesaid latex a coagulating agent of the group consisting of alcoholscontaining from 3 to 12 carbon atoms, mixtures of the said alcohols withketones containing from 3 to 12 carbon atoms, and mixtures of the saidalcohols with liquid hydrocarbons wherein the said coagulating agent isa liquid at the coagulating temperature and has a solubility in water atthe coagulating temperature varying from the solubility of diamyl etherto the solubility of methyl ethyl ketone at the coagulating temperatureand the solubility of the polymer in the said coagulating agent at thecoagulating temperature does not exceed that of the solubility of thepolymer in methyl ethyl ketone at the coagulating temperature, in anamount sufiicient to form a separate organic phase and then heating theresulting mixture to boiling for a few minutes to bring about thecoagulation of the dispersed polymer.

3. A process for coagulating a stable weakly alkaline latex of a vinylchloride polymer which latex has been prepared by polymerizing the vinylchloride in a true aqueous emulsion containing water, the vinyl chlorideand, as the sole emulsifying agent, from 0.5% to 5% by weight based onthe water of an ionic surface active agent which is organic solventstable and alkali stable, which comprises adding to the said latex acoagulating agent consisting of an alcohol containing from 3 to 12carbon atoms wherein the said coagulating agent is a liquid at thecoagulating temperature and has a solubility in water at the coagulatingtemperature varying from the solubility of diamyl ether to thesolubility of methyl ethyl ketone at the coagulating temperature and thesolubility of the polymer in the said coagulating agent at thecoagulating temperature does not exceed that of the solubility of thepolymer in methyl ethyl ketone at the coagulating temperature, in anamount which is in excess of that which is suflicient to form a separateorganic phase, heating the resulting mixture to boiling for a fewminutes to bring about coagulation of the polymer, and then distillingoff a portion of the said coagulating agent so that the aqueous layer isclear.

4. The process as defined in claim 3 wherein the coagulating agent isisoamyl alcohol.

5. A process for coagulating a stable emulsion containing 15% to 33% byweight of a polymer of vinyl chloride dispersed therein which emulsionhas been prepared by polymerizing the monomer in alkaline true aqueousemulsion containing water, the monomer and as the sole emulsifying agentfrom 0.5% to 5% by weight based on the water of an ionic surface activeagent which is organic solvent stable and alkali stable, which comprisesadding to the said emulsion a coagulating agent of the group consistingof alcohols containing from 3 to 12 carbon atoms, mixtures of the saidalcohols with ketones containing from 3 to 12 carbon atoms, and mixturesof the said alcohols with liquid hydrocarbons wherein the saidcoagulating agent is a liquid at the coagulating temperature and has asolubility in water at the coagulating temperature varying from thesolubility of diamyl ether to the solubility of methyl ethyl ketone atthe coagulating temperature, and the solubility of the polymer in thesaid coagulating agent at the coagulating temperature does not exceedthat of the solubility of the polymer in methyl ethyl ketone at thecoagulating temperature, in an amount which is sufficient to form aseparate organic phase and then heating the resulting mixture to boilingfor a few minutes to bring about the coagulation of the dispersedpolymer.

6. The process as defined in claim 5 wherein the coagulant is secondaryhexyl alcohol.

7. The process as defined in claim 5 wherein the coagulant is a mixtureof isoamyl alcohol and methyl ethyl ketone.

8. The process as defined in claim 5 wherein the coagulant is a mixtureof isoamyl alcohol and gasoline having a boiling range of IOU-120 C.

9. A process for coagulating a stable emulsion containing about 15% to33% by weight of a vinyl chloride polymer prepared by polymerizing themonomer in an aqueous emulsion having a pH of 7 to 9 and containing asthe sole emulsifying agent a member of the group consisting of an alkalimetal alkyl sulfate and alkali metal alkyl sulfonate which comprisesadding about 6 vol. percent of isoamyl alcohol which amount issufficient to form a separate organic phase and then heating theresulting mixture to boiling to bring about the coagulation of the vinylchloride polymer.

10. A process for coagulating a stable emulsion containing about 15% to33% by weight of a vinyl chloride polymer prepared by polymerizing themonomer in an aqueous emulsion having a pH of '7 to 9 and contains asthe sole emulsifying agent a member of the group consisting of an alkalimetal alkyl sulfate and alkali metal alkyl sulfonate which comprisesadding approximately 10 vol. percent of isoamyl alcohol which issufficient to form a separate organic phase, heating the mixture toboiling for a few minutes and then distilling of the isoamyl alcoholuntil the amount of the alcohol is below that required to form the clearaqueous layer.

EGBERT CORNELIS HENDRIK KOLVOORT.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,096,609 Daniel Oct. 19,. 1937 2,373,347 Schoenfield Apr. 10,1942 2,538,273 Rhines Jan. 6, 1951 2,567,678 Morrison Sept. 11, 1951

1. A PROCESS FOR COAGULATING A STABLE LATEX OF A VINYL CHLORIDE POLYMERWHICH LATEX HAS A PH OF AT LEAST 7 AND HAS BEEN PREPARED BY POLYMERIZINGTHE SAID VINYL CHLORIDE IN A TRUE AQUEOUS EMULSION CONTAINING WATER, THEVINYL CHLORIDE AND, AS THE SOLE EMULSIFYING AGENT, FROM 0.5% TO 5% BYWEIGHT BASED ON THE WATER OF AN IONIC SURFACE ACTIVE AGENT WHICH ISORGANIC SOLVENT STABLE AND ALKALI STABLE, WHICH COMPRISES ADDING TO THESAID LATEX A COAGULATING AGENT OF THE GROUP CONSISTING OF ALCOHOLSCONTAINING FROM 3 TO 12 CARBON ATOMS, MIXTURES OF THE SAID ALCOHOLS WITHKETONES CONTAINING FROM 3 TO 12 CARBON ATOMS, AND MIXTURES OF THE SAIDALCOHOLS WITH LIQUID HYDROCARBONS WHEREIN THE SAID COAGULATING AGENT ISA LIQUID AT THE COAGULATING TEMPERATURE AND HAS A SOLUBILITY IN WATER ATTHE COAGULATING TEMPERATURE VARYING FROM THE SOLUBILITY OF DIAMYL ETHERTO THE SOLUBILITY OF METHYL ETHYL KETONE AT THE COAGULATING TEMPERATUREAND THE SOLUBILITY OF THE POLYMER IN THE SAID COAGULATING AGENT AT THECOAGULATING TEMPERATURE DOES NOT EXCEED THAT OF THE SOLUBILITY OF THEPOLYMER IN METHYL ETHYL KETONE AT THE COAGULATING TEMPERATURE, IN ANAMOUNT WHICH IS SUFFICIENT TO FORM A SEPARATING ORGANIC PHASE ANDHEATING THE MIXTURE OF AQUEOUS DISPERSION AND ADDED COAGULATING AGENT ATA TEMPERATURE AT LEAST ABOUT 50* C. TO BRING ABOUT THE COAGULATION OFTHE DISPERSED POLYMER.